Page 727 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

702 CHAPTER 3

VetBooks.ir 3.161 3.162

Fig. 3.162 Cytology of BAL fluid from a horse
with heaves during exacerbation of clinical signs.
Well-preserved neutrophils (black arrows) are
Fig. 3.161 Bronchoscopic view of the carina in a horse the predominant cell type. Pulmonary alveolar
with heaves during severe exacerbation of clinical signs. macrophages are also visible (red arrow).
The carina is markedly blunted due to oedema, and
flecks of mucus are visible. Airways are hyperresponsive,
resulting in excessive coughing and constriction of the fluticasone) routes of administration (Table 3.4).
airways in response to passage of the bronchoscope. Oral administration of prednisone should be
avoided because it is poorly absorbed, and the active
metabolite is not reliably produced in many horses.
Management More severely affected animals will require initial
Clinical cure is not generally possible in horses with therapy with systemically administered corticoste-
heaves, so treatment is aimed at achieving and main- roids before inhaled corticosteroids are considered.
taining remission from clinical signs. This is best A tapering course of corticosteroid administration
done through persistent and aggressive environ- over 2–4 weeks is commonly required.
mental management to reduce exposure to inhaled During episodes of heaves exacerbation, rescue
allergens (Table 3.3). Hay should be good quality therapy may be required in animals demonstrat-
with minimal dust and moulds present, or preferably ing dyspnoea or respiratory distress. This is best
changed to haylage, or the animal may benefit from achieved through bronchodilation with rapid- acting
transition to a pelleted complete feed. Continuous drugs such as beta-2 adrenergics (e.g. albuterol,
pasture turnout is recommended to optimise venti- levalbuterol, salbutamol, clenbuterol), followed by
lation. If the animal is to be housed indoors for any longer-acting bronchodilation (e.g. salmeterol).
period of time, effort should be made to avoid peri- Chronic use of beta-agonist medications such as
ods of dusty activities such as during cleaning and clenbuterol leads to tolerance or desensitisation to
bedding of stalls, feeding hay and sweeping. The the drug, and current recommendations are to limit
stall should also not be located near to an arena or use to 2 weeks.
hay-storage facility; overhead hay storage is particu- One controlled study showed improvement of
larly detrimental. Bedding should be wood shavings clinical signs of heaves after administration of an
or peat moss rather than straw or sawdust. omega-3 polyunsaturated fatty acid supplement con-
Alleviation of lung inflammation is achieved taining docosahexaenoic acid (1.5–3 g) and a low-dust
through therapy with corticosteroids given via oral diet for 2 months. Some practitioners report using
(e.g. prednisolone), parenteral (e.g. isoflupredone, skin allergen testing or serum antibody testing to
dexamethasone) or inhalation (e.g. beclomethasone, direct allergen desensitisation treatment, but there